The Tdap vaccination is a combination vaccine that protects against three potentially life-threatening bacterial diseases: tetanus, diphtheria, and pertussis (whooping cough) and is a back-to-school institution for middle schoolers from the ages of 10 to 13. (File photo)

Four years ago, California was in the grips of an outbreak of pertussis, the contagious disease also known as whooping cough because of the “whoop” sound characterizing the deep breathing that follows violent coughing attacks.

Given the cyclical nature of the disease — outbreaks tend to occur every three to five years — epidemiologists in the Southern California region have anticipated another surge right about now.

But there are no signs as yet of an epidemic, statewide or locally.

So, if you are a parent who recently got notice from your child’s school that someone on campus has been diagnosed with pertussis, take the recommended precautions but don’t panic that the disease is spreading like wildfire.

Fewer cases statewide

In a snapshot taken as of May 20, the California Dept. of Public Health’s last report on pertussis case counts shows there are about 180 fewer cases statewide so far this year than at the same time period in 2017. The 1,109 year-to-date cases are way down from the peak of 4,455 in 2014.

A check with public health departments in Los Angeles, Orange, Riverside and San Bernardino counties also indicates that with one exception, the number of pertussis cases in 2018 are about the same — or lower — than last year.

The outlier is Orange County, where there were 80 reported cases versus 46 cases at this time in 2017.

“We haven’t reached the same levels seen in the 2014 epidemic year (407 cases), but reports are definitely increasing,” said Dr. Matt Zahn, Orange County’s medical director of epidemiology and assessment. “Many of these cases have been in children, but there hasn’t been an outbreak identified at a single school.”

An increase was not surprising, Zahn said.

“On a national level, communities and states have noted that case rates wax and wane in intervals of about 4 to 5 years,” he said. “California pertussis rates have been lower since the epidemic year of 2014, so on a statewide level we’ve anticipated that we may be seeing an increase in pertussis in the near future.”

Killer of thousands

Once common in the United States, whooping cough killed thousands of people and caused hundreds of thousands to become ill year after year until the introduction of a vaccine in the 1940s. Then cases dropped to fewer than 5,000 a year. At the peak of the most recent outbreak in California, there were 11,209 cases.

Even children who have had their vaccines can come down with the disease since vaccine protection can decrease over time, said Dr. Shobita Rajagopalan, in a letter emailed June 4 to notify parents with children attending Calle Mayor Middle School in Torrance that at least one person on campus had been diagnosed with whooping cough.

The last outbreak at a school in Los Angeles County occurred in March 2017 and, overall, the case count in the county is not expected to reach that of previous years, according to the Los Angeles County Department of Public Health.

Vaccination rates are at a level where an average elementary, middle or high school student population may not experience any pertussis cases — or at the most, one to three cases — in a single year.

Pertussis recommendations

To prevent the spread of pertussis after a case has been reported, the L.A. County Department of Public Health recommends:

1. If your child is coughing please keep them out of school until they have a note from a doctor that shows your child is safe to return.

2. If your child begins coughing over the next 3 weeks please take them to a doctor and let the doctor know that your child may have been exposed to pertussis.

3. If your child is medically exempt from the TDAP or Pertussis vaccine please consult your doctor. Let your doctor know that your child may have been exposed to Pertussis. It may be recommended that your child take antibiotics or stay home from school for 21 days.

In Pasadena, which like Long Beach has its own health department and is not included in the Los Angeles County data, there have been no confirmed laboratory cases of pertussis so far in 2018. Health care specialists with the Long Beach Department of Health and Human Services also attributed a low case count — less than 10 from January to May — to vaccine rates and booster shots.

“We were expecting a busy year this year, but actually it’s been kind of slow,” said Long Beach epidemiologist Nora Barin.

With 35 cases reported as of June 6, Riverside County was on track to reach about the same number of cases — 72 — as in 2017, said Barbara Cole, a registered nurse who is the county’s director for disease control.

San Bernardino County’s last increase in pertussis cases dates back to the epidemic in 2014, when 205 cases were reported. In 2016, the caseload had dropped to 32, “so an increase in cases is expected in late 2018 or early 2019,” said Lana Cao, public health information officer at the county’s Department of Public Health.

“Vaccination is the best method to prevent pertussis,” Cao said. “Of note is the recommendation for women to have a Tdap vaccination in the third trimester of each pregnancy. Infants less than 4 months of age are at the greatest risk, being too young to be fully vaccinated.”

Theresa Walker is a Southern California native who has been a staff writer at The Orange County Register since 1992. She specializes in human interest stories and social issues, such as homelessness. She also covers nonprofits and philanthropy in Orange County. She loves telling stories about ordinary people who do the extraordinary in their communities.